The invention relates to a hollow shaft, which has external profilings for torque transmission at its two ends, e.g., splines, wedge-shaped teeth, polygonal profiles or the like, such that the shaft sections therebetween have a smaller diameter than the profilings.
Hollow shafts of this type can be used to drive units such as oil pumps, where, for space reasons, the center section is thinner than the toothed ends.
One proposed method to produce such shafts was to form them as a single part using cold extrusion. In this case, however, one of the profilings would have to be re-expanded after the forming of the hollow shaft section. Such expansions can only be done in special, highly complex tools and require a substantial amount of additional work thereafter. This would have caused substantial additional costs.